DEVELOPMENT OF THE ACCUMULATIONAL GEOMORPHOLOGY OF THE SPITS DIAOLONGZUI
Cai Aizhi(Institute of Oceanology, Academia Sinica)
Diaolongzui lies in the center of eastern coast of the Laizhou Bay. In the coastal plain there is an old coastline. They are many date revealing this old coastline: 1. The 5 m isometric line is a continuous, distinctive cliff, with a relative height of 1-2 meters; 2. Over the cliff is a slight slop consisting of a Q3dpl yellow stratum. On the Q3dpl slop, neither feature of marine erosion nor tract of marine accumulation is showing; 3. Below the old cliff is a Q4m mixture of sands, conchs and muds.Conditions under which the multi-accumulation spits were formed are as follows: A great bulk of the sands supplied from the Wanghe river, some supplied from the eastern coast of the Laizhou Bay, and the carrying by the wave and longshore current to the southwest.Accumulational forms ①-⑨ are developed in sequence. Behind each form there is a lagoon or marsh. After form ⑥ was developed, form @ undergoes a process of retreat from ④ to ⑤.On the formation of small barrier inland we favered Hoyts hypothesis that the small barrier island may be formed by spit growth across a lagoon and subsequent truncation of the spit during storms. For examples: a. Form ⑧ was truncated by storm into a small inlet and island forty two years ago; b. The smallest spit ⑦ was truncated into a smallest inlet and island in February, 1979 by a strong northern wind.